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 Post subject: Rails, scoop ,rocker, for low wind hydrofoil board?
PostPosted: Tue May 27, 2014 9:08 pm 
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Joined: Sun Feb 24, 2008 6:15 pm
Posts: 335
Location: France
I have built many hydrofoils and am pleased with them.
I have never made a board.
I want to make a board for low wind foiling.
I have a shape in mind but ask these questions?
Remember the goal is to get enough board speed up to get up on the foil.
Any ideas on rocker, rail shapes and scoop?
Concave, convex?
We start to get up at about 7 knots or so of wind and once up the foil takes over so the board is not that important,
BUT,
it is VERY important to have as little h20 friction when trying to get up to lift off speed.
Any and all ideas ,suggestions more than welome!!
Do you think board volume as in liters displaced plays a role?
thanx R H :thumb:


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 Post subject: Re: Rails, scoop ,rocker, for low wind hydrofoil board?
PostPosted: Wed May 28, 2014 6:50 am 
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Joined: Mon Jul 01, 2013 7:16 am
Posts: 336
Location: Perth, Australia
I have no idea:)

But, for a fast surface, low friction, you might try Crown Durasurf topsheet which you glue on the bottom.

You might also try a cardboard (that is a kitchen laminate which they glue on). Cardboard comes in any surface you can imagine.

I've placed a piece of cardboard in a cup of water for two weeks and it stayed well. Distorted but strong.

Good luck.

PS
You can also have just epoxy. But polished for example with a very fine metal wool. This makes a fast surface.


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 Post subject: Re: Rails, scoop ,rocker, for low wind hydrofoil board?
PostPosted: Wed May 28, 2014 6:59 am 
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Joined: Tue Feb 24, 2009 1:43 pm
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Location: Iv.G.-Slovenia
Alalia shape?
Narrow and fast, super fast planing.
Do not do a concave or bottom taper around the outline, however do compensate the taper by doing a bit more rocker.


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 Post subject: Re: Rails, scoop ,rocker, for low wind hydrofoil board?
PostPosted: Wed May 28, 2014 10:44 am 
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Joined: Wed Sep 11, 2013 3:51 pm
Posts: 61
I know nothing about foiling, but if all you are looking for is a stable platform to get enough speed to get up on the foil, then I would consider the following:

A displacement hull like a surfboard or race board would not sink even if there's no wind, and you would need less of a power stroke to get going.
Less rocker is more efficient.
Flat profile (no convex or concave) is more efficient.

Rocker, outline, concave, flex, edge shape - all these things are probably more relevant to a normal board that spends most of its time in contact with the water.


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 Post subject: Re: Rails, scoop ,rocker, for low wind hydrofoil board?
PostPosted: Wed May 28, 2014 2:51 pm 
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Joined: Thu Jun 05, 2003 3:37 am
Posts: 2421
The trend is wide flat and beveled rails and sometimes beveled nose, idea being the bevel helps the board pop back out when the foil dips momentarily. Obviously flat and wide helps in getting to 7-8 knots quickly so the foil pops up easily.

The other extreme is minimalist, just enough board to stand on -this must be hard to start and jibe!

In between, there are the surfboards that can mount a foil, and be useful without it as well when there's no wind at all, or too much wind for foiling. To me this sounds best.
I have the fantasy of a foil I could slap on my surfboard, ride upwind a few miles to a good wave, remove the foil, stow it somehow and ride waves conventionally back downwind. Masts are too long though...


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 Post subject: Re: Rails, scoop ,rocker, for low wind hydrofoil board?
PostPosted: Wed May 28, 2014 5:25 pm 
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Joined: Sun Feb 24, 2008 6:15 pm
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Location: France
BWD wrote:
The trend is wide flat and beveled rails and sometimes beveled nose, idea being the bevel helps the board pop back out when the foil dips momentarily. Obviously flat and wide helps in getting to 7-8 knots quickly so the foil pops up easily.



In between, there are the surfboards that can mount a foil, and be useful without it as well when there's no wind at all, or too much wind for foiling. To me this sounds best.

I have the fantasy of a foil I could slap on my surfboard, ride upwind a few miles to a good wave, remove the foil, stow it somehow and ride waves conventionally back downwind. Masts are too long though...


BWD
I like your idea check out http://www.3gcomposite.com/boutique/pro ... ubrique=41
If that does not work search ketos foil misc products
55 cm and strut demounts fuse as well as wings, maybe an idea for your upwind to waves on foil, also perfect as foils go upwind like nothing else, and downwind on your surf with foil in a back pack.
Juat an idea for you.
I agree with flat and wide, thanx!
The other nice thing with your idea is you can choose maybe only 1 front foot strap for the foil and quickly emove for your strapless surf session. :!:
R H


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